The present invention relates to an apparatus for liquid treatment, for instance textile material dyeing in a vessel or several communicating vessels in which a processing liquid can be caused to flow through the textile material, or the textile material can be moved through the processing liquid, and the textile material vessel or vessels are separated from a chamber containing a heating or cooling medium, the arrangement being such that the heating or cooling medium chamber is open at the top end thereof and communicates with the vessel, and that openings for dispersing said heating or cooling medium are arranged at the upper portion of said chamber, and that at least one outlet is arranged at the bottom of the chamber.
When dyeing textile material, particularly synthetic material, the temperature of the processing bath is to be raised to a temperature level of, for instance, 105.degree.-130.degree. C. Previously, the heating has been carried out either indirectly by arranging a heat exchanger in the pressure vessel, with the heat exchanger being surrounded by processing liquid, or by arranging heat exchangers directly into the circulation path of the processing liquid. When heating indirectly, a relatively large volume of liquid is required since the liquid has to flow around the heat exchanger pipes and a bath ratio of 1:10 to 1:12 is obtained, i.e. 1 kg textile material requires 10-12 1 processing liquid. From an economical and environmental aspect, large liquid volumes are unfavorable since said volumes require greater amounts of energy for heating and imply a greater amount of discharge water which is to be purified. A further drawback of heating indirectly is the nonhomogenous heat distribution.
Further on, when heating directly, particular constructive measures are to be taken for making possible the cooling of the processing bath since it is not possible to add a cooling medium directly to the processing bath.